High strength
In order to improve the ability of Kunshan spring to resist fatigue damage and relaxation, Kunshan spring material should have high yield strength and elastic limit, especially high yield strength ratio. In general, the elastic limit of the material is directly proportional to the yield strength, so Kunshan spring designers and manufacturers always hope that the material has a high yield strength.
Good plasticity and toughness
In the manufacturing process of Kunshan spring, the material needs to undergo different degrees of processing deformation, so it is required to have certain plasticity. For example, for the hook and loop and torsion arm of the tension and torsion Kunshan spring with complex shape, when the radius of curvature is very small, the Kunshan spring material shall not have defects such as crack and damage during processing, winding or stamping and bending. At the same time, when Kunshan spring bears impact load or variable load, the material should have good toughness, which will be of great benefit to improve the service life of Kunshan spring
Excellent surface condition and fatigue performance
The surface of Kunshan spring bears great stress when working, and fatigue damage often starts from the surface of steel wire. For Kunshan spring used in important occasions, such as valve Kunshan spring, valve Kunshan spring and suspension Kunshan spring, it is required to have a cycle life of several million times, tens of millions of times or even longer, which puts forward high requirements for the fatigue performance of materials. There are many factors that affect the fatigue performance of materials, such as the chemical composition, hardness, purity of steel, surface quality and metallographic structure, and the surface quality of materials is particularly important.
Strict size
Many Kunshan springs have high requirements for load accuracy. For example, the load deviation of the valve Kunshan spring shall not be greater than 5% - 6% of the specified load. Take the tension and compression Kunshan spring with round steel wire as an example, if the diameter deviation of the steel wire is 1%, the load will have a deviation of about 4%. Therefore, strict dimensional accuracy is also very important to ensure the quality of Kunshan spring.
Good uniformity
The uniformity requirements for materials refer to the uniform and stable requirements for chemical composition, mechanical properties, dimensional deviation and other indicators of materials. If the properties of materials are inconsistent in all aspects, it will bring great difficulties to the production of Kunshan spring, resulting in the discreteness of product geometric dimension, hardness, load and other parameters, and serious non-uniformity may even cause waste products.
